Measures of circadian preference in childhood and adolescence: A review

Factor structure of the Brazilian version of the Morningness-Eveningness Scale for Children (MESC) for chronotype assessment in adolescents

To translate and adapt the Morningness-Eveningness Scale for Children into Brazilian Portuguese, translation, back-translation, technical review, expert evaluation, focus group, test-retest, and factorial structure of the instrument were performed. The total sample consisted of 676 students from the 6th to 9th grade of elementary school and from the 1st to 3rd year of high school, aged between 10 and 19 years, 343 girls (51%) and 333 boys (49%), with a mean age of 13.98 (2.00) years. Of these, 40 students from the 6th grade, aged between 10 and 13 years, participated in the test-retest, 24 girls (60%) and 16 boys (40%), with a mean age of 11.17 (0.50) years. Descriptive and inferential analyses were performed, including exploratory and confirmatory factor analyses. High levels of internal consistency (α = 0.742) and test-retest (0.974) were obtained, in addition to high values for clarity of language (0.88), practical relevance (1.00) and theoretical relevance (1.00). In the confirmatory factor analysis, the model presented satisfactory validity indices: χ2 = 40.811 (df = 34), p = 0.196, RMSEA = 0.025 (90% CI: <0.001-0.049), CFI = 0.990 and TLI = 0.987, with no need for adjustments between the covariances between the items. Therefore, the MESC-BR was considered an adequate instrument to assess circadian preferences in Brazilian adolescents, given its test-retest psychometric properties and construct validity.

Feasibility of an At-Home Experimental Circadian Misalignment Induction for Adolescents

Despite extensive research on the effects of sleep restriction on adolescent health, the field lacks experimental methods to study the health effects of mistimed sleep, which is also common among adolescents. This paper describes a novel 3-week experimental protocol that was designed to compare sleep restriction, like what many adolescents experience on school nights, against sleep that meets the recommended duration but is timed to be relatively aligned or misaligned with their circadian phase. Healthy 14-18-year-olds, classified as early ("Lark") and late ("Owl") chronotypes, entered a six-night chronotype-aligned stabilization condition, followed by five nights of sleep restriction, a return to the stabilization schedule, and five nights of healthy sleep duration (HS). During HS, participants were randomly assigned to early-to-bed versus late-to-rise arms, intended to align with or misalign with their circadian phase. Actigraphy monitored sleep, and weekly dim-light melatonin onset (DLMO) assessed circadian phase. Analyses confirmed that the protocol met five key validation metrics related to differential attrition, sleep timing, circadian phase, and experimental induction of HS that is timed to be relatively aligned vs. misaligned with circadian phase. This protocol appears useful for future research into how misaligned sleep patterns, which occur regularly for many adolescents, may impact health.

Validation of the Morningness-Eveningness Scale for Children (MESC) with ambulatory circadian monitoring of temperature, light exposure and activity

The external validity of the Morningness-Eveningness Scale for Children was analysed via objective measures of skin temperature, light exposure and motor activity with the ambulatory circadian monitoring methodology. A total of 138 adolescents (57 boys and 81 girls) aged 12-13 years, who in addition to completing the Morningness-Eveningness Scale for Children to determine their circadian typology wore a wrist activity device (Kronowise 3.0; Kronohealth SL) during school days and a weekend, participated. Circadian parameters, such as mesor, amplitude and acrophase, were estimated for skin temperature, light exposure and motor activity, as were sleep parameters, such as risetime, bedtime and social jetlag. The results indicated that during the weekend E-type adolescents experienced later acrophases in temperature, light and activity than I-type and M-type adolescents did, whereas boys experienced earlier acrophases in temperature and activity. When school weekdays were compared with the weekend, there was a weekend delay in the acrophases of temperature (1:03), light exposure (2:03) and activity (3:15). The results obtained in this study provide external validity for applying the Morningness-Eveningness Scale for Children in the naturalistic context of high school while considering sex and type-of-day differences as important variables in chronopsychological studies.

External validity of the reduced Morningness-Eveningness Questionnaire for Children and Adolescents: an actigraphic study

The aim of this study was to examine the external validity of the reduced Morningness-Eveningness Questionnaires for Children and Adolescents, using circadian motor activity, assessed through actigraphy, as an external criterion. Overall, 458 participants (269 females), with a mean (standard deviation) age of 15.75 (1.16) years, took part in this study. Each adolescent was requested to wear the actigraph Micro Motionlogger Watch actigraph (Ambulatory Monitoring, Inc., Ardlsey, NY, USA) around the non-dominant wrist for 1 week. At the end of the actigraphic recording, participants completed the reduced Morningness-Eveningness Questionnaires for Children and Adolescents. We extracted the motor activity counts, minute-by-minute over the 24 h, to depict the 24-h motor activity pattern, and we adopted the statistical framework of functional linear modelling to examine its changes according to chronotype. According to the reduced Morningness-Eveningness Questionnaires for Children and Adolescents cut-off scores, 13.97% of participants (n = 64) belonged to the evening-types category, 9.39% (n = 43) to morning-types, while the remaining (76.64%, n = 351) to the intermediate-types category. Evening types moved significantly more than the intermediate and morning types from around 10:00 p.m. to 2:00 a.m., while the opposite pattern of results was observed around 4:00 a.m. The results highlighted a significant difference in the 24-h motor activity pattern between chronotypes, in line with the expectations based on their well-known behaviour. Therefore, this study shows that the external validity of the reduced Morningness-Eveningness Questionnaire for Children and Adolescents, established by considering motor activity (recorded through actigraphy) as an external criterion, is satisfactory.

[Overview of chronobiological and sleep medical aspects of depression in adolescents]

Changes in sleep are reported in adolescents with depression with a frequency of up to 71%. Aspects of chronobiology and sleep based on the current scientific literature are illustrated and summarized in this narrative review. The circadian clock synchronizes organisms to the light-dark structure of the environment. The individual synchronization is called "chronotype." Chronotype changes according to age, among other factors, and adolescents experience the latest chronotypes overall. The potential discrepancy between internal and external time is called "social jetlag." Social jetlag is especially pronounced during adolescence. It is associated with numerous health risks, such as depression. Changes in sleep behavior in affective disorders and its comorbidity to depression have also been well described in the literature. In this article, underlying concepts from chronobiology and sleep medicine are initially summarized. Then, health risks of disrupted sleep-wake behavior are described, and connections to depression specifically during adolescence are drawn. The article concludes with clinical recommendations for sleep disorders and depression during adolescence as well as suggestions for further research.

Dynamic modelling of chronotype and hypo/manic and depressive symptoms in young people with emerging mental disorders

There is significant interest in the possible influence of chronotype on clinical states in young people with emerging mental disorders. We apply a dynamic approach (bivariate latent change score modelling) to examine the possible prospective influence of chronotype on depressive and hypo/manic symptoms in a youth cohort with predominantly depressive, bipolar, and psychotic disorders (N = 118; 14-30-years), who completed a baseline and follow-up assessment of these constructs (mean interval = 1.8-years). Our primary hypotheses were that greater baseline eveningness would predict increases in depressive but not hypo/manic symptoms. We found moderate to strong autoregressive effects for chronotype (β = -0.447 to -0.448, p < 0.001), depressive (β = -0.650, p < 0.001) and hypo/manic symptoms (β = -0.819, p < 0.001). Against our predictions, baseline chronotypes did not predict change in depressive (β = -0.016, p = 0.810) or hypo/manic symptoms (β = 0.077, p = 0.104). Similarly, the change in chronotype did not correlate with the change in depressive symptoms (β = -0.096, p = 0.295) nor did the change in chronotype and the change in hypo/manic symptoms (β = -0.166, p = 0.070). These data suggest that chronotypes may have low utility for predicting future hypo/manic and depressive symptoms in the short term, or that more frequent assessments over longer periods are needed to observe these associations. Future studies should test whether other circadian phenotypes (e.g. sleep-wake variability) are better indicators of illness course.

The psychometric properties of the Spanish version of the Morningness-Eveningness Stability Scale improved (MESSi) in adolescents

The aim of the present study was to adapt the Morningness-Eveningness-Stability Scale improved (MESSi) to the Spanish adolescent population, testing its factor structure and construct validity. The participants were 725 adolescents (52.9% girls; M = 14.8, SD = 1.99) who completed the MESSi, the Morningness Eveningness Scale of Children (MESC), questions about sleep habits adapted from the School Sleep Habits Survey, and self-reported academic performance. The psychometric results support a three-factor model with the factors of morning affect, eveningness, and distinctness, which show good internal consistency. The pattern of correlations between MESSi and the other measures was in the expected direction. The MESC correlated positively with morning affect and negatively with eveningness, whereas distinctness was uncorrelated. Boys reported higher morningness, whereas girls reported higher distinctness. Eveningness was negatively related to academic performance. Overall, the results support the validity and reliability of the Spanish adolescent version of the MESSi.

Regularity and Timing of Sleep Patterns and Behavioral Health Among Adolescents

OBJECTIVE

Sleep is vital to supporting adolescent behavioral health and functioning; however, sleep disturbances remain under-recognized and undertreated in many health care settings. One barrier is the complexity of sleep, which makes it difficult for providers to determine which aspects-beyond sleep duration-may be most important to assess and treat to support adolescent health. This study examined associations between 2 sleep indices (regularity and timing) and adolescent behavioral health and functioning over and above the impact of shortened/fragmented sleep.

METHOD

Eighty-nine adolescents recruited from the community (mean age = 14.04, 45% female participants) completed 7 days/nights of actigraphy and, along with a parent/guardian, reported on behavioral health (internalizing and externalizing symptoms) and psychosocial functioning. Stepwise linear regressions examined associations between sleep timing and regularity and behavioral/functional outcomes after accounting for shortened/fragmented sleep.

RESULTS

Delayed sleep timing was associated with greater self-reported internalizing (F[6,82] = 11.57, p = 0.001) and externalizing (F[6,82] = 11.12, p = 0.001) symptoms after accounting for shortened/fragmented sleep. Irregular sleep was associated with greater self-reported and parent-reported externalizing symptoms (self: F[7,81] = 6.55, p = 0.01; parent: F[7,80] = 6.20, p = 0.01) and lower psychosocial functioning (self: F[7,81] = 6.03, p = 0.02; parent: F[7,78] = 3.99, p < 0.05) after accounting for both shortened/fragmented sleep and delayed sleep timing.

CONCLUSION

Sleep regularity and timing may be critical for understanding the risk of poor behavioral health and functional deficits among adolescents and as prevention and intervention targets. Future work should focus on developing and evaluating convenient, low-cost, and effective methods for addressing delayed and/or irregular adolescent sleep patterns in real-world health care settings.

A systematic review and meta-analysis of sleep and circadian rhythms disturbances in individuals at high-risk of developing or with early onset of bipolar disorders

Sleep and circadian rhythms disturbances (SCRD) in young people at high risk or with early onset of bipolar disorders (BD) are poorly understood. We systematically searched for studies of self, observer or objective estimates of SCRD in asymptomatic or symptomatic offspring of parents with BD (OSBD), individuals with presentations meeting recognised BD-at-risk criteria (BAR) and youth with recent onset of full-threshold BD (FT-BD). Of 76 studies eligible for systematic review, 35 (46%) were included in random effects meta-analyses. Pooled analyses of self-ratings related to circadian rhythms demonstrated greater preference for eveningness and more dysregulation of social rhythms in BAR and FT-BD groups; analyses of actigraphy provided some support for these findings. Meta-analysis of prospective studies showed that pre-existing SCRD were associated with a 40% increased risk of onset of BD, but heterogeneity in assessments was a significant concern. Overall, we identified longer total sleep time (Hedges g: 0.34; 95% confidence intervals:.1, .57), especially in OSBD and FT-BD and meta-regression analysis indicated the effect sizes was moderated by the proportion of any sample manifesting psychopathology or receiving psychotropic medications. This evolving field of research would benefit from greater attention to circadian rhythm as well as sleep quality measures.

Validity of chronotype questionnaires in adolescents: Correlations with actigraphy

There are only a few validated chronotype and morningness-eveningness questionnaires for adolescents. We evaluated three such questionnaires, namely Morningness-Eveningness Stability Scale improved; reduced Morningness-Eveningness Questionnaire for Children and Adolescents; and Composite Scale of Morningness in adolescents against actigraphy. Fifty-five healthy 13- to 16-year-old adolescents completed the Morningness-Eveningness Stability Scale improved, reduced Morningness-Eveningness Questionnaire for Children and Adolescents, Composite Scale of Morningness, and Pediatric Daytime Sleepiness Scale, and provided a 7-day actigraphy and sleep diary recording about their sleep-wake patterns. We examined the correlations between sleep-wake and activity parameters, and the questionnaires. The influence of age and sex on chronotype classification was studied using uni- and multivariate analyses. All three chronotype questionnaires showed good internal consistency and convergent validity. Spearman correlations reflected less daytime sleepiness, earlier sleep times, midpoints of sleep, and acrophase in morning-oriented participants. Evening-oriented participants had more sleepiness and later respective sleep-wake times. Chronotype classification differed significantly between questionnaires. The Composite Scale of Morningness classified more participants as morning types when compared with the reduced Morningness-Eveningness Questionnaire for Children and Adolescents (12 versus 7, respectively), and fewer adolescents as evening types (5 versus 9, respectively). Age and sex had no significant influence on questionnaire scores. The Morningness-Eveningness Stability Scale improved, reduced Morningness-Eveningness Questionnaire for Children and Adolescents, and Composite Scale of Morningness are valid instruments to determine circadian preference in adolescents; however, chronotype classification from the Composite Scale of Morningness and reduced Morningness-Eveningness Questionnaire for Children and Adolescents cannot be used interchangeably.

Integrative Identification of Genetic Loci Jointly Influencing Diabetes-Related Traits and Sleep Traits of Insomnia, Sleep Duration, and Chronotypes

Accumulating evidence suggests a relationship between type 2 diabetes mellitus and sleep problems. A comprehensive study is needed to decipher whether shared polygenic risk variants exist between diabetic traits and sleep traits. Methods: We integrated summary statistics from different genome-wide association studies and investigated overlap in single-nucleotide polymorphisms (SNPs) associated with diabetes-related traits (type 2 diabetes, fasting glucose, fasting insulin, and glycated hemoglobin) and sleep traits (insomnia symptoms, sleep duration, and chronotype) using a conditional/conjunctional false discovery rate approach. Pleiotropic genes were further evaluated for differential expression analysis, and we assessed their expression pattern effects on type 2 diabetes by Mendelian randomization (MR) analysis. Results: We observed extensive polygenic pleiotropy between diabetic traits and sleep traits. Fifty-eight independent genetic loci jointly influenced the risk of type 2 diabetes and the sleep traits of insomnia, sleep duration, and chronotype. The strongest shared locus between type 2 diabetes and sleep straits was FTO (lead SNP rs8047587). Type 2 diabetes (z score, 16.19; P = 6.29 × 10⁻⁵⁹) and two sleep traits, sleep duration (z score, −6.66; P = 2.66 × 10⁻¹¹) and chronotype (z score, 7.42; P = 1.19 × 10⁻¹³), were shared. Two of the pleiotropic genes, ENSA and PMPCA, were validated to be differentially expressed in type 2 diabetes, and PMPCA showed a slight protective effect on type 2 diabetes in MR analysis. Conclusions: Our study provided evidence for the polygenic overlap between diabetic traits and sleep traits, of which the expression of PMPCA may play a crucial role and provide support of the hazardous effect of being an “evening” person on diabetes risk.

Probing different aspects of short and ill-timed sleep in adolescents using the Morningness-Eveningness Scale for Children

Sleep problems among adolescents are believed to be related to the circadian changes that occur at this age. Therefore, most self-report instruments that measure sleep patterns in adolescence focus solely on measuring circadian rhythms. However, sleep-wake cycles reflect both circadian and homeostatic processes. Recently, it was shown that answers to the Morningness-Eveningness Questionnaire for adults, which is used to assess circadian typology, were able to identify three interrelated latent factors: two that can be conceptualized as homeostatic (sensitivity to the build-up of sleep pressure and efficiency of dissipation of sleep pressure) and a less well-defined factor related to activity preference time (APT). To better understand self-reported changes in sleep patterns in adolescents we applied confirmatory factor analysis to explore whether responses to the Morningness-Eveningness Scale for Children (MESC) could also identify these three factors. The sample comprised 397, 9- to 17-year-olds. A three-correlated and a bifactor-(S-1) model (with sleep onset characteristics as a reference factor) had acceptable/good fit indices. This indicates that the MESC captures dissociable, but interrelated, homeostatic and circadian processes in addition to APT. These factors correlated with corresponding reported sleep habits, showing individual differences that may be more associated with sleep difficulties than the effects of age, which only correlated very modestly with some sleep habits. Our results indicate that the MESC can show distinct individual differences in three sleep factors that can help identify adolescents at higher risk of sleep-related problems that may require factor-specific interventions.

Factor structure and psychometric properties of the Persian versions of the Pediatric Daytime Sleepiness Scale and Morningness-Eveningness Scale for Children

BACKGROUND

The Pediatric Daytime Sleepiness Scale (PDSS) and the Morningness-Eveningness Scale for Children (MESC) are widely used to measure two important facets of sleep patterns, but neither have been adapted and validated for use in Iran. The purpose of this study was to examine the psychometric properties and factor structure of the Persian versions of the PDSS and the MESC in a sample of Iranian adolescents.

MATERIALS AND METHODS

The Persian versions of PDSS and MESC were translated and administered to a representative sample (n = 407) of Iranian early adolescents, aged 9-15 years, who attended school in morning shifts. The factor structure of both scales, found in prior studies, was tested using Confirmatory Factor Analyses to assess their validity and reliability.

RESULTS

The results revealed that the model fit indices of the one factor solution of the PDSS and the two factor solution of the MESC were acceptable to good. A high Pearson correlation was found between raw and latent factor scores for the PDSS and the two factors derived from the MESC (i.e., Morningness and Planning). Furthermore, the higher the PDSS score (more daytime sleepiness), the lower the MESC scores (more eveningness), indicating criterion validity of the scales showing the expected increase in daytime sleepiness in evening oriented adolescents who wake up early for attending school.

CONCLUSION

The Persian versions of the PDSS and the MESC can be considered reliable and valid tools for evaluating, respectively, daytime sleepiness and morningness-eveningness in the adolescent population of Iran.

Daylight Saving Time preferences in Norway: Do individual chronotype and home address' latitude and longitude matter?

Daylight Saving Time is highly debated and associated with several health risks. Health experts recommend terminating adjusting the clock time, and to keep permanent standard (winter) time year around. The aims of the study were to investigate preferences for keeping or terminating this biannual adjustment of clock times and for permanent standard or summer time, in the general Norwegian population. Furthermore, we aimed to investigate whether such preferences depended on individual chronotype and home address' latitude/longitude. The online survey included 47,194 participants. Chronotype was measured with the Composite Scale of Morningness (morning types, intermediate types, evening types). Results showed that 78.2% preferred to terminate adjusting the clock time. Summer time year around was preferred by 61.5% whereas 29.1% preferred standard time year around, and 9.4% did not have any preference. Preferences for terminating adjustment of clock times and summer time year around were found in all chronotypes and regardless of living south (latitude 58-59°N), north (latitude 69-71°N), west (longitude 5-6°E) or east (longitude 19-31°E). However, a relatively larger proportion of evening chronotypes preferred to terminate adjusting the clock time compared to morning chronotypes, and relatively more people living north or east preferred termination than people living south or west, respectively. Permanent standard time was more strongly preferred by extreme morning types in comparison with the other chronotypes. In conclusion, nearly four out of five participants reported to prefer to terminate adjusting the clock time, in line with recommendations. However, in contrast to advice from health experts, permanent summer time was preferred by twice as many as permanent standard time. Both chronotype and home address' latitude and longitude mattered in regard to such preferences, but only to a small degree.

Circadian preference and intelligence - an updated meta-analysis

A large number of previous studies reported a link between circadian preference and psychometric intelligence with mixed results and various hypotheses about the source of this correlation. In this study, we aimed to update a previous meta-analysis about the correlation between circadian preference and intelligence. Our literature search identified a large number of new studies, resulting in an increase of over 100% in the number of studies and over 400% in the number of involved participants (total k = 30, total N = 11160) over the previous meta-analysis, sampling a much wider age range from children to adults in late middle age. Our meta-analysis revealed no significant link between morningness and intelligence (r = -0.008) when the entire sample was studied, and no evidence for publication bias. This overall effect, however, obscured the moderating effect of age. The morningness-intelligence correlation decreased with mean sample age (R² = 54%), ranging from a non-significant positive trend in children and adolescents to a significant negative correlation after young adulthood. Eveningness was positively correlated with intelligence (r = 0.056), but this finding is based on a more age-restricted sample and only reached significance with some model specifications. We hypothesize that the age-moderated correlation between circadian preference and intelligence reflects social effects, where more intelligent individuals are more able to adjust their daily schedules to their natural circadian rhythm.

A daily diary study of sleep chronotype among Mexican-origin adolescents and parents: Implications for adolescent behavioral health

The current study used daily assessments of sleep to examine stability and change in sleep chronotype in adolescents and their parents. The study assessed adolescent sleep chronotype according to age, gender, and parent chronotype, and evaluated its associations with emotional and behavioral problems in youth. Participants included of 417 Mexican American adolescents (Mage = 16.0 years, Range = 13.9-20.0) and 403 caregivers, who reported bed and wake times daily for 2 consecutive weeks at two time points spaced 1 year apart. In addition, adolescents completed established self-report questionnaires of emotional and behavioral problems. Chronotype was computed as the midsleep point from bed to wake time on free days, correcting for sleep debt accumulated across scheduled days. Multilevel modeling showed a curvilinear association between adolescent age and chronotype, with a peak eveningness observed between ages 16 to 17. Adolescent and parent chronotypes were contemporaneously correlated, but each was only moderately stable over the 1-year period. Later adolescent chronotype was contemporaneously associated with more substance use in all adolescents. Individual development and the family context shape sleep chronotype in adolescents and parents. Sleep chronotype is implicated in adolescent behavioral health.

The search for causality of personality-chronotype associations: insights from a one-year longitudinal study of adolescents

Associations between certain personality traits and individual differences in diurnal preferences, referred to as morningness-eveningness, are well established from cross-sectional studies. However, it is unclear whether personality affects diurnal preference, diurnal preference affects personality, or some third factor influences both. The current study assessed the Big Five personality traits and morningness-eveningness in a one-year, two-wave longitudinal design, in a sample of 169 Polish high school students (59% females), aged 16-17 years (M = 16.80, SD = 0.39) during the first wave of measurement. During the second wave the participants were respectively 1 year older. Cross lagged panel analyses were run to determine wave 1 predictors of wave 2 variables. Cross-sectional analyses replicated the association between morningness and conscientiousness that has been reliably found in previous studies, but the cross-lagged paths between these variables were nonsignificant. These two traits appear to be intrinsically linked to one another by adolescence, possibly as a consequence of genetic influences that shape temperament earlier in childhood. In contrast, emotional stability and morningness were not significantly correlated in wave 1 cross-sectional data, but a significant relationship was found in the cross-lagged panel analysis. Wave 1 emotional stability predicted wave 2 morningness, although wave 1 morningness did not predict personality. We tentatively suggest that there may be a causal effect of personality on diurnal preference, associated with avoidance strategies for coping with academic stress as the high school years approach their end. More neurotic individuals may cope with their aversion to classes by distracting themselves with evening pursuits, such as use of the internet. Further work might examine in more depth how contextual stressors interact with personality to affect daily activities at different times of the day.

Self-reported seasonality is strongly associated with chronotype and weakly associated with latitude

The aim of this study was to investigate the association between self-reported seasonality, i.e., seasonal variations in mood and related behavior, and chronotype, and between self-reported seasonality and home address' latitude. Data were collected from an online questionnaire with 45,338 participants. Seasonality and chronotype were measured with the Global Seasonality Score (GSS) and the Composite Scale of Morningness, respectively. The participants were categorized into extreme morning types, moderate morning types, intermediate types, moderate evening types, and extreme evening types. Furthermore, participants were categorized depending on home address' latitude. Data were analyzed with chi-square tests and logistic regression analyses adjusting for sex, age, marital status, level of education, and children living at home. Results showed that high seasonality (GSS 11+) was found in 20.9%. The prevalence dose-dependency ranged from 12.2% in extreme morning types to 42.6% in extreme evening types (adjusted OR = 4.21, CI = 3.27-5.41). The prevalence was higher in participants living in North-Norway (latitude from 65 to 71⁰N) versus South-Norway (latitude from 58 to 65⁰N) (23.8% versus 20.7%; adjusted OR = 1.18, CI = 1.08-1.28). When comparing the northernmost (69-71⁰N) to the southernmost (58-59⁰N) counties of Norway, the association was stronger (24.9% versus 18.7%; adjusted OR = 1.37, CI = 1.20-1.56). Among the adjusting variables, high seasonality was associated with female sex, younger age, being unmarried, low level of education, and not having children living at home. In conclusion, about one in five Norwegians reported high seasonality. High seasonality was strongly associated with late chronotype (being an evening type) and weakly associated with living in the north (high latitude).

Angry night birds: Emotionality, activity and sociability temperament in adolescent chronotypes

There is growing interest in personality profiles associated with morningness-eveningness to foster an understanding of the behaviors and mental states of chronotypes. This study aimed to analyze the domains of emotionality, activity and sociability (EAS) temperament in relation to morningness-eveningness in adolescents. A sample of 539 school pupils aged 13-19 years completed the EAS Temperament Survey, the Composite Scale of Morningness and the Munich Chronotype Questionnaire. Amongst the five EAS domains (emotionality-distress, emotionality-fearfulness, emotionality-anger, activity and sociability), greater emotionality-anger was related to eveningness, while greater emotionality-distress was related to lower social jet lag. The results suggest that evening chronotypes can be temperamentally inclined to anger. The possible mechanisms of this association are discussed.

In-field assessment of sodium oxybate effect in pediatric type 1 narcolepsy: an actigraphic study

Study Objectives

Sodium oxybate (SXB) is a GABAergic agent widely used as off-label treatment in pediatric type 1 narcolepsy (NT1). Here, we aimed at analyzing by wrist actigraphy the sleep/wake profile of NT1 children and adolescents in drug-naïve condition and after 1 year of SXB treatment. As secondary aim, we investigated changes on sleepiness, cataplexy, and children's anthropometric profile after 1 year of SXB treatment.

Methods

Twenty-four drug-naïve NT1 children underwent 7 days of actigraphy during the school week. Information on sleepiness, narcolepsy symptoms, and anthropometric features were collected during the same week with questionnaires and semistructured clinical interview. Children started SXB treatment and underwent a second evaluation encompassing actigraphy, clinical interview, questionnaires, and anthropometric assessment after 1 year of stable treatment.

Results

Actigraphy effectively documented an improvement of nocturnal sleep quality and duration coupled with a reduction of diurnal total sleep time, nap frequency, and duration at 1 year follow-up. Reduction of sleepiness, cataplexy frequency and severity, and weight loss, mainly in obese and overweight NT1 children, were also observed at the 1 year follow-up.

Conclusions

Actigraphy objectively documented changes in nocturnal sleep quality and diurnal napping behavior after 1 year of SXB treatment, thus representing a valid approach to ecologically assess SXB treatment effect on NT1 children's sleep/wake profile. NT1 symptoms severity and children's anthropometric features also changed as expected. Actigraphy offers the possibility to longitudinally follow up children and has potential to become a key tool to tailor treatment in pediatric patients.

A systematic review on sleep alterations anticipating the onset of bipolar disorder

Background:

Sleep alterations are frequent occurrence in Bipolar Disorder (BD), both in acute and interepisodic phases. Sleep alterations have been also described both long before BD onset, as aspecific risk syndromes, or as immediate prodromes of BD onset. The aim of the present study is to systematically review the relationship between sleep alterations anticipating for the full-blown onset of BD, both in general and according to specific polarities of onset.

Methods:

A systematic literature research according to PRISMA statement and considering: 1. prospective studies about BD patients’ offspring with sleep alterations who later developed BD. 2. prospective studies assessing patients with sleep disorders who later developed BD. 3. retrospective studies on BD patients where sleep alterations before BD onset of the disease were reported.

Results:

A total of 16 studies were included in this review. Sleep disturbances may frequently appear 1 year before the onset of BD or more, often during childhood or adolescence. A decreased need for sleep may precede the onset of the illness, specially a manic episode, while insomnia appears to anticipate either a manic or a depressive episode. Hypersomnia seems to precede bipolar depressive episodes.

Conclusions:

Sleep alterations frequently appear long before the onset of BD, and appear to be related specifically to the polarity of the index episode. The detection and treatment of sleep alterations in special high risk populations may help achieving an earlier detection of the illness.

Sleep Timing in Patients with Precocious and Delayed Pubertal Development

Previous studies have reported a shift in the timing of sleep during adolescence toward a later time. To date, it is unclear whether hormonal changes during puberty might contribute to this change in sleeping behavior. We systematically assessed pubertal development and sleep timing in a cross-sectional case-control study in girls with precocious (n = 42) and boys with delayed pubertal development (n = 19). We used the Munich ChronoType Questionnaire and the Children’s ChronoType Questionnaire to assess sleep timing in patients and age- and sex-matched controls (n = 309) and used the midpoint of sleep on free days, corrected for potential sleep debt accumulated during the school week, as a marker for sleep timing. Compared to the controls, girls with central precocious puberty showed a delay in sleep timing of 54 min, and girls with premature pubarche slept on average 30 min later. Male adolescents with delayed pubertal development showed an average sleep midpoint that was 40 min earlier compared to the control group. The results of this pilot study suggest an association between pubertal onset and shifts in sleep timing, which is a novel finding in human sleep behavior. Prospective studies in larger cohorts will be needed to examine the robustness and generalizability of the findings.

Mind-wandering, or the allocation of attentional resources, is sleep-driven across childhood

Mind-wandering or the spontaneous, uncontrolled changes in the allocation of attention resources (lapses) may cause variability in performance. In childhood, the relationship between the activation state of the brain, such as in attentional performance, and sleep has not been explored in detail. We investigated the role of sleep in attentional performance, and explored the most important parameters of their relationship. We objectively measured momentary lapses of attention of 522 children and correlated them with sleep schedules. In the subgroup of young children (age 7.1 ± 0.6 years; 60.8% girls), increasing age, long sleep duration and assessment closer to the previous night’s sleep period was associated with impaired performance speed and consistency. From pre-adolescence (age 9.4 ± 0.8 years; 50.5% girls) onwards somno-typologies may develop. As a result, in adolescence (age 13.4 ± 1.2 years; 51.3% girls) not only sleep duration but also sleep midpoint and sleep regularity influence the individual speed and stability of attention. Across development, regularity of sleep, individual sleep midpoint and bedtime become increasingly important for optimal performance throughout the day. Attentional performance and sleep shared almost half of their variance, and performance was sleep-driven across childhood. Future studies should focus on intra- and inter-individual differences in sleep-wake behavior to improve performance or decrease mind-wandering in youth by targeting sleep habits.

Drowsy Driving, Sleep Duration, and Chronotype in Adolescents

OBJECTIVE

To determine whether self-reported drowsy driving was associated with an evening chronotype, a biologically-based difference in circadian sleep-wake timing, and shorter school-night sleep duration in a sample of high school drivers.

STUDY DESIGN

Cross-sectional observational data were obtained from an online survey in spring 2015 of 431 drivers, age 15.5-18.7 years, attending Fairfax County (Virginia) Public schools. Drowsy driving was defined as having ever "driven a car or motor vehicle while feeling drowsy" in the last year. School-night sleep duration was calculated from school-night bedtime and wake time. Those with scores in the lower and upper tertiles of the Morningness-Eveningness Scale for Children were designated as having an evening or morning chronotype, respectively.

RESULTS

Among survey respondents, 63.1% drove at least several times a week and 47.6% reported drowsy driving. The covariate-adjusted prevalence of drowsy driving was 13.9% (95% CI 3.0%-24.9%) higher in students who slept <7 hours on school-nights than in those who slept 8 or more hours. Compared with those with a morning chronotype, the adjusted prevalence of drowsy driving was 15.2% (95% CI 4.5%-25.9%) higher among those with an evening chronotype.

CONCLUSION

Among adolescent drivers, both an evening chronotype and shorter school-night sleep duration were associated with more frequent reports of drowsy driving. Interventions to improve the timing and duration of nighttime sleep in adolescents may reduce the occurrence of drowsy driving.

Psychometric properties of a Japanese version of Composite Scale of Morningness

This study aimed to assess the factor structure and validity of the Composite Scale of Morningness (CSM) in Japanese samples. A sample of 348 Japanese university students (196 men, 152 women) and 170 adults from the community (50 men, 120 women) completed a questionnaire including the CSM, the Diurnal Type Scale (DTS) and questions regarding sleeping and waking times. Four measurement models were compared, and a two-factor measurement model with Morningness/Time of day preference (α = 0.78) and Morning Affect/Alertness (α = 0.80) factors yielded the closest fit. Both Morningness/Time of day preference and Morning Affect/Alertness were positively correlated with DTS score. Morningness/Ttime of day preference was negatively correlated with the midpoint of sleep on weekdays and free days. The measurement model was invariant across the university and community groups. The community group, which was older, was characterized by greater morningness. The results provide evidence of the validity of the Japanese CSM, thus opening up the possibility of including Japanese samples in cross-cultural research on morningness.

Could long-term administration of melatonin to prepubertal children affect timing of puberty? A clinician's perspective

Exogenous melatonin can be used to treat sleep disturbance in adults, children, and adolescents. While its short-term use is considered safe, there are some concerns that long-term use might delay children's sexual maturation, possibly by disrupting the decline in nocturnal melatonin levels that occur at the onset of puberty. This narrative review aimed to summarize some of the current knowledge about the potential effects of exogenous melatonin on puberty. We found no clinical studies that experimentally tested the effects of melatonin on pubertal timing in children, but we reviewed the small number of observational studies. We also drew on animal data to try to answer our question. The photoperiod and melatonin-mediated seasonal transitions in sexual activity and breeding in some mammals across the seasons have been used as a model of sexual development in mammals, including humans. The switch from non-sexual activity (in the non-breeding period) to sexual activity (in the breeding period) has been likened to the onset of puberty as there are similarities between the two. We conclude that to investigate an association between melatonin and pubertal timing, it will be important to conduct long-term randomized controlled trials of latency age children and also examine the cellular and systems-level interactions between melatonin and kisspeptin, a recently identified neuropeptide with a locus of action at the gonadotropin releasing hormone neurons that is important in contributing to the timing of puberty onset.

Daytime midpoint as a digital biomarker for chronotype in bipolar disorder

BACKGROUND

Bipolar disorder (BD) is associated with later sleep and daily activity (evening rather than morning chronotype). Objective chronotype identification (e.g., based on actigraphs/smartphones) has potential utility, but to date, chronotype has mostly been assessed by questionnaires. Given the ubiquity of accelerometer-based devices (e.g. actigraphs/smartphones) worn/used during daytime and tendency to recharge rather than wear at night, we assessed chronotype using daytime (rather than sleep) interval midpoints.

METHODS

Sixty-one participants with BD type I (BD-I) or II (BD-II) and 61 healthy controls completed 25-50 days of continuous actigraphy. The Composite Scale of Morningness (CSM) was completed by a subset of this group. Daytime activity midpoint was calculated for each daytime interval, excluding naps. Evening chronotype was defined as having a daytime interval midpoint at or after 16:15:00 (4:15:00 PM).

RESULTS

BD versus controls had delayed daytime midpoint (mean ± standard deviation) (16:49:07 ± 01:26:19 versus 16:12:51 ± 01:02:14, p < 0.01), and greater midpoint variability (73.3 ± 33.9 min versus 58.1 ± 18.3 min, p < 0.01). Stratifying by gender and age, females and adolescents with BD had delayed and more variable daytime midpoints versus controls. Adults with BD had greater midpoint variability than controls. Within-person mean and standard deviations of daytime midpoints were highly correlated with sleep midpoints (r = 0.99, p < 0.01 and r = 0.86, p < 0.01, respectively). Daytime midpoint mean was also significantly correlated with the CSM (r = -0.56, p < 0.01).

LIMITATIONS

Small sample size; analyses not fully accounting for daytime napping.

CONCLUSIONS

Wrist actigraphy for determination of daytime midpoints is a potential tool to identify objective chronotype. Exploration of the use of consumer devices (wearables/smartphones) is needed.

Eveningness diurnal preference associated with poorer socioemotional cognition and social functioning among healthy adolescents and young adults

Recently there has been growing interest in associations between sleep, emotion, and social functioning. Less is known about relationships between chronotype preference and socioemotional cognition and functioning, particularly among adolescents, who experience dramatic normative shifts in diurnal preference, affective functioning, and social competence. Fifty-five healthy adolescents and young adults completed a self-report chronotype preference measure, a computerized measure of socioemotional cognition, and a semi-structured clinical interview assessing interpersonal functioning. Greater eveningness preference was associated with poorer socioemotional cognition and social functioning in this age group. Future studies should assess these relationships across development and using objective measures of circadian timing.

How Young “Early Birds” Prefer Preservation, Appreciation and Utilization of Nature

Since the 1990s, the Two Major Environmental Value model (2-MEV) has been applied to measure adolescent environmental attitudes by covering two higher order factors: (i) Preservation of Nature (PRE) which measures protection preferences and (ii) Utilization of Nature (UTL) which quantifies preferences towards exploitation of nature. In addition to the 2-MEV scale, we monitored the Appreciation of Nature (APR) which, in contrast to the UTL, monitors the enjoyable utilization of nature. Finally, we employed the Morningness–Eveningness Scale for Children (MESC) which monitors the diurnal preferences and associates with personality and behavioral traits. In this study, we analyzed data from 429 Irish students (14.65 years; ±1.89 SD) with the aim of reconfirming the factor structure of the 2-MEV+APR and monitoring the relationship between the MESC and the environmental values (PRE, UTL, APR). Our findings identified a significant association between PRE and APR with MESC. In addition, we observed a gender difference. Our results suggest that morningness preference students are more likely to be protective of and appreciative towards nature. Recommendations for outreach programs as well as conclusions for environmental education initiatives in general are discussed.

Physical Activity and Sleep/Wake Behavior, Anthropometric, and Metabolic Profile in Pediatric Narcolepsy Type 1

Objectives: Regular physical activity is routinely recommended in children and adolescents suffering from narcolepsy type 1 (NT1), but controlled studies analyzing its influence on sleep/wake behavior, metabolic, and anthropometric profile in pediatric NT1 are lacking. Methods: Fifty consecutive drug-naïve NT1 children and adolescents were assessed through actigraphic, clinical, and metabolic evaluations. Patients were compared with respect to their engagement in leisure-time physical activities (LTPA): patients engaged in LTPA (n = 30) and patients not engaged (No-LTPA, n = 20), respectively. Results: LTPA patients presented lower BMI, with different BMI categories distribution and higher HDL cholesterol, when compared with No-LTPA subjects. Increased night-sleep duration, higher sleep quality, and reduction of nap frequency were documented through actigraphy in LTPA subjects. Subjective sleepiness, as measured by ESS-CHAD, was also lower in LTPA subjects while cataplexy frequency proved similar between the two groups. Discussion: In pediatric NT1 patients, regular engagement in LTPA is associated with significant differences on sleepiness, anthropometric and metabolic profile and objectively assessed sleep/wake behavior. Engagement in LTPA is beneficial and should be strongly encouraged in pediatric NT1 patients.

Chronotype, social jet lag, sleep debt and food timing in inflammatory bowel disease

The preference of the sleep/wake cycle can be grouped into categories or chronotypes. Inflammatory bowel disease (IBD) has been linked to poor sleep quality which correlates with disease severity. Social jet lag (SJL) is the difference between sleep timing on work and free days and is a marker for circadian misalignment which has been linked to increased inflammation. We investigated whether chronotype, SJL, sleep debt (SD), and food timing were associated with an IBD specific complications and a lower quality of life. Overall, 191 subjects (115 IBD subjects and 76 healthy controls (HC)) completed the Pittsburgh Sleep Quality Index (PSQI), Morningness-Eveningness Questionnaire (MEQ), Munich ChronoType Questionnaire (MCTQ), Short Inflammatory Bowel Disease Questionnaire (SIBDQ), and a structured Food Timing Questionnaire. Later chronotype (by MEQ) was associated with a worse SIBDQ (r = -0.209; P < 0.05). SJL was increased in IBD at 1.32 h ± 1.03 vs. 1.05 h ± 0.97 in HC, P < 0.05, when adjusted for age. SJL (>2 h) was present in 40% of severe/complicated Crohn's patients (fistulizing or structuring Crohn's or history of Crohn's related surgery) compared to only 16% of uncomplicated Crohn's patients (P < 0.05). Sleep debt was increased in IBD subjects compared to HC at 21.90 m ± 25.37 vs. 11.49 m ± 13.58, P < 0.05. IBD subjects with inconsistent breakfast or dinner times had lower SIBDQ scores (4.78 ± 1.28 vs. 5.49 ± 1.02, P < 0.05; 4.95 ± 0.31 vs. 5.42 ± 0.32, P < 0.05 respectively). In summary, later chronotype, and markers of circadian misalignment (social jet lag, sleep debt, and inconsistent meal timing) were associated with IBD disease specific complications and/or lower quality of life.

Subjective versus objective evening chronotypes in bipolar disorder

BACKGROUND

Disturbed sleep timing is common in bipolar disorder (BD). However, most research is based upon self-reports. We examined relationships between subjective versus objective assessments of sleep timing in BD patients versus controls.

METHODS

We studied 61 individuals with bipolar I or II disorder and 61 healthy controls. Structured clinical interviews assessed psychiatric diagnoses, and clinician-administered scales assessed current mood symptom severity. For subjective chronotype, we used the Composite Scale of Morningness (CSM) questionnaire, using original and modified (1, ¾, ⅔, and ½ SD below mean CSM score) thresholds to define evening chronotype. Objective chronotype was calculated as the percentage of nights (50%, 66.7%, 75%, or 90% of all nights) with sleep interval midpoints at or before (non-evening chronotype) vs. after (evening chronotype) 04:15:00 (4:15:00a.m.), based on 25-50 days of continuous actigraph data.

RESULTS

BD participants and controls differed significantly with respect to CSM mean scores and CSM evening chronotypes using modified, but not original, thresholds. Groups also differed significantly with respect to chronotype based on sleep interval midpoint means, and based on the threshold of 75% of sleep intervals with midpoints after 04:15:00. Subjective and objective chronotypes correlated significantly with one another. Twenty-one consecutive intervals were needed to yield an evening chronotype classification match of ≥ 95% with that made using the 75% of sleep intervals threshold.

LIMITATIONS

Limited sample size/generalizability.

CONCLUSIONS

Subjective and objective chronotype measurements were correlated with one another in participants with BD. Using population-specific thresholds, participants with BD had a later chronotype than controls.

What predicts inattention in adolescents? An experience-sampling study comparing chronotype, subjective, and objective sleep parameters

OBJECTIVE

Many adolescents sleep insufficiently, which may negatively affect their functioning during the day. To improve sleep interventions, we need a better understanding of the specific sleep-related parameters that predict poor functioning. We investigated to which extent subjective and objective parameters of sleep in the preceding night (state parameters) and the trait variable chronotype predict daytime inattention as an indicator of poor functioning.

METHODS

We conducted an experience-sampling study over one week with 61 adolescents (30 girls, 31 boys; mean age = 15.5 years, standard deviation = 1.1 years). Participants rated their inattention two times each day (morning, afternoon) on a smartphone. Subjective sleep parameters (feeling rested, positive affect upon awakening) were assessed each morning on the smartphone. Objective sleep parameters (total sleep time, sleep efficiency, wake after sleep onset) were assessed with a permanently worn actigraph. Chronotype was assessed with a self-rated questionnaire at baseline. We tested the effect of subjective and objective state parameters of sleep on daytime inattention, using multilevel multiple regressions. Then, we tested whether the putative effect of the trait parameter chronotype on inattention is mediated through state sleep parameters, again using multilevel regressions.

RESULTS

We found that short sleep time, but no other state sleep parameter, predicted inattention to a small effect. As expected, the trait parameter chronotype also predicted inattention: morningness was associated with less inattention. However, this association was not mediated by state sleep parameters.

CONCLUSIONS

Our results indicate that short sleep time causes inattention in adolescents. Extended sleep time might thus alleviate inattention to some extent. However, it cannot alleviate the effect of being an 'owl'.

From Lark to Owl: developmental changes in morningness-eveningness from new-borns to early adulthood

Morningness-eveningness or chronotype changes significantly throughout the life span. This has been reported for the transition during adolescence in some studies, and to a lesser extent in early adulthood. Primary and pre-school children have been under investigation in fewer studies. This is the first comprehensive study covering the age range from very young children until early adulthood (0-30 years) based on the same measurement instrument. Here, we show that the turn towards eveningness starts at an early age in German children. Based on 26,214 cross-sectional data, we further show that at the end of adolescence, morningness-eveningness does not significantly change during early adulthood. Sex differences arise during puberty and remain until 30 years. The breaking point for the turn towards morningness is 15.7 years in girls and 17.2 boys. At the age of 0-1 years, there are about 70% morning types, and about 1% evening types, while at the age of 16 years, only 5% are morning types and 19% are evening types.

Self-Regulation and Sleep Duration, Sleepiness, and Chronotype in Adolescents

OBJECTIVE

To determine whether shorter school-night sleep duration, greater daytime sleepiness, and greater eveningness chronotype were associated with lower self-regulation among adolescents.

METHODS

An online survey of 7th- to 12th-grade students in 19 schools in Fairfax County, Virginia Public Schools was conducted in 2015. Self-regulation was measured with the Behavior Rating Inventory of Executive Function, 2nd edition, Screening Self-Report Form. Sleep measures included school night-sleep duration (hours between usual bedtime and wake time), daytime sleepiness (Sleepiness Scale in the Sleep Habits Survey, tertiles), and chronotype (Morningness-Eveningness Scale for Children, continuous score and tertiles). Sociodemographic factors and mental health conditions were analyzed as potential confounders.

RESULTS

Among 2017 students surveyed, the mean age was 15.0 years (range, 12.1-18.9 years), and 21.7% slept <7 hours on school nights. In regression models adjusted for confounders, there was a significant independent association between self-regulation and both chronotype (P < .001) and daytime sleepiness (P < .001) but not sleep duration (P = .80). Compared with those in the lowest tertile of daytime sleepiness, those in the highest tertile had lower (0.59 SD units; 95% confidence interval, 0.48-0.71) self-regulation, as did those in the eveningness tertile of chronotype compared with those in the morningness tertile (0.35 SD units lower; 95% confidence interval, 0.24-0.46).

CONCLUSIONS

Among adolescents, greater daytime sleepiness and greater eveningness chronotype were independently associated with lower self-regulation, but shorter sleep duration was not. Aspects of sleep other than school-night sleep duration appear to be more strongly associated with self-regulation.

Circadian Rest-Activity Rhythm in Pediatric Type 1 Narcolepsy

STUDY OBJECTIVES

Pediatric type 1 narcolepsy is often challenging to diagnose and remains largely undiagnosed. Excessive daytime sleepiness, disrupted nocturnal sleep, and a peculiar phenotype of cataplexy are the prominent features. The knowledge available about the regulation of circadian rhythms in affected children is scarce. This study compared circadian rest-activity rhythm and actigraphic estimated sleep measures of children with type 1 narcolepsy versus healthy controls.

METHODS

Twenty-two drug-naïve type 1 narcolepsy children and 21 age- and sex- matched controls were monitored for seven days during the school week by actigraphy. Circadian activity rhythms were analyzed through functional linear modeling; nocturnal and diurnal sleep measures were estimated from activity using a validated algorithm.

RESULTS

Children with type 1 narcolepsy presented an altered rest-activity rhythm characterized by enhanced motor activity throughout the night and blunted activity in the first afternoon. No difference was found between children with type 1 narcolepsy and controls in the timing of the circadian phase. Actigraphic sleep measures showed good discriminant capabilities in assessing type 1 narcolepsy nycthemeral disruption.

CONCLUSIONS

Actigraphy reliably renders the nycthemeral disruption typical of narcolepsy type 1 in drug-naïve children with recent disease onset, indicating the sensibility of actigraphic assessment in the diagnostic work-up of childhood narcolepsy type 1.

Differences in sleep disturbances among offspring of parents with and without bipolar disorder: association with conversion to bipolar disorder

OBJECTIVES

Disruptions in sleep and dysregulation in circadian functioning may represent core abnormalities in the pathophysiology of bipolar disorder (BP). However, it is not clear whether these dysfunctions are state or trait markers of BP. This report compared sleep and circadian phenotypes among three groups: offspring of parents with BP diagnosed with BP at intake (BP/OB; n = 47), offspring of parents with BP without BP at intake (non-BP/OB; n = 386), and offspring of matched control parents who did not have BP (controls; n = 301). We also examined the association of baseline sleep parameters with subsequent development of BP among the non-BP/OB group.

METHODS

Pittsburgh Bipolar Offspring Study youth (ages 6-18 years) and their parents completed assessments every two years pertaining to the child's sleep and circadian phenotypes and current psychopathology. Mixed-effects models examined differences in baseline sleep and circadian variables among the three groups.

RESULTS

BP/OB offspring who were in a mood episode differed significantly on sleep parameters from the non-BP/OB and the offspring of controls, such as having inadequate sleep. Mixed logistic regression procedures showed that baseline sleep and circadian variables, such as frequent waking during the night, significantly predicted the development of BP among non-BP/OB over longitudinal follow-up.

CONCLUSIONS

While lifetime diagnostic status accounted for differences among the groups in sleep and circadian disturbances, psychopathology explained the differences even further. Additionally, sleep disturbance may be a prognostic indicator of the development of BP in high-risk youth. Future studies are required to further disentangle whether sleep and circadian disruption are state or trait features of BP.